1. Technical Field of the Invention
The present invention relates to a technology for analyzing rhythms of pieces of music.
2. Description of the Related Art
A technology for analyzing the rhythm of music (i.e., the structure of a temporal array of musical sounds) in order to realize music comparison or search has been suggested in the art. For example, Jouni Paulus and Anssi Klapuri, “Measuring the Similarity of Rhythmic Patterns”, Proc. ISMIR 2002, p. 150-156 describes a technology in which the time sequence of the feature amount of each of unit periods (frames) having a predetermined time length, into which an audio signal is divided, is compared between different pieces of music. A DP matching (Dynamic Time Warping (DTW)) technology, which specifies corresponding locations on the time axis (i.e., corresponding time-axis locations) in pieces of music, is employed to compare the feature amounts of pieces of music.
However, the technology disclosed by Jouni Paulus and Anssi Klapuri, “Measuring the Similarity of Rhythmic Patterns”, Proc. ISMIR 2002, p. 150-156 has a problem in that the amount of data required to compare pieces of music is large since a feature amount extracted in each unit period of audio signals is used to compare rhythms of pieces of music. In addition, since a feature amount extracted in each unit period is set regardless of the tempo of music, an audio signal extension/contraction process such as the above-mentioned DP matching should be performed to compare the rhythms of pieces of music, causing high processing load.